User Manual

AirLink Pro T1/E1 Rack Mount Installer’s Guide
Glossary
Rev. B - 1/97
D-2
A Ampere: A unit of electrical current related to the actual
number of electrons moving past a given point per second.
AIS Alarm Indication Signal. To maintain transmission
continuity, an Alarm Indication Signal (AIS) is transmitted
to the network upon Loss of Signal (LOS) or Loss of Clock
(LOC). It is halted when the triggering signal is terminated.
An AIS is an unframed, all-ones signal.
AMI Alternate Mark Inversion. A signal encoded according to the
AMI method is a bipolar pseudo-ternary signal conveying
binary digits (bits) in which successive “marks” are normally
of alternating polarity, positive and negative. This is the
traditional method of encoding DS1 signals.
antenna A transmitting or receiving device for radiated waves. The
antenna acts as a form of matching transformer for waves
along a line and waves in space so that the maximum transfer
of energy can be achieved.
antenna gain Antenna gain is a measure of the efficiency of an antenna
compared with the efficiency of a standard reference
antenna. The efficiency is measured in terms of the power
radiated or received in a given direction as compared with
the standard under the same conditions.
Azimuth The angle in the horizontal ground plane with respect to true
North (i.e., horizontal direction); used in reference to antenna
alignment.
B8ZS Bipolar with Eight-Zero Substitution. This coding scheme is
one of the methods used to avoid long strings of zeroes in a
bipolar DS1 signal entering the network from the DTE. In
B8ZS, every string of eight zeroes is replaced by a special
code for transmission over networks that are sensitive to long
strings of zeroes. The code contains a pattern of bipolar
violations that is identified by the recipient and then
removed in the decoding process to recreate the original string
of zeroes. This particular method of coding is the evolving
standard, but is not yet fully supported by all carriers.
baud Baud is a unit for measuring signaling rate for a digital
signal, used similarly to bits per second (bps) for low-speed
data.